Remote data multicasting and remote direct memory access over optical fabrics

Abstract

Today's communications require an effective yet scalable way interconnection of data centers and warehouse scale computers (WSCs) whilst operators must provide a significant portion of data center and WSC applications free of charge to users and consumers. At present, data center operators face the requirement to meet exponentially increasing demand for bandwidth without dramatically increasing the cost and power of the infrastructure employed to satisfy this demand. Simultaneously, consumer expectations of download/upload speeds and latency in accessing content provide additional pressure. Accordingly, the inventors provide a number of optical switching fabrics which reduce the latency and microprocessor loading arising from the prior art Internet Protocol multicasting techniques.

What is claimed is: 
     
         1 . A method of multicasting comprising:
 providing a passive optical cross-connect fabric;   providing a set of first nodes, each first node connected to an input port of the passive optical cross-connect fabric and transmitting on a predetermined wavelength of a set of wavelengths;   providing a set of second nodes, each second node connected to an output port of the passive optical cross-connect fabric; and   transmitting data from a predetermined subset of the set of first nodes to a predetermined subset of the set of second nodes using a direct memory access protocol; wherein   all messages broadcast by each first node of the set of first nodes are broadcast to all second nodes of the set of second nodes.   
     
     
         2 . The method according to  claim 1 , wherein
 the direct memory access protocol is a remote direct memory access protocol.   
     
     
         3 . The method according to  claim 1 , wherein
 the direct memory access protocol is a layer-4 transport protocol based upon a remote direct memory access datagram.   
     
     
         4 . The method according to  claim 1 , wherein
 a message loss ratio of messages transmitted is better than one or more of one in a billion, one in ten billion, one in fifty billion, and one in sixty billion.   
     
     
         5 . The method according to  claim 1 , wherein
 an end-to-end latency is less than 8 μs with 10 Gb/s Ethernet network adapters.   
     
     
         6 . The method according to  claim 1 , wherein
 an end-to-end latency is less than 2 μs with 10 Gb/s Ethernet network adapters.   
     
     
         7 . The method according to  claim 1 , wherein
 the passive optical cross-connect fabric does not include any optical switching elements.   
     
     
         8 . The method according to  claim 1 , wherein
 the passive optical cross-connect fabric is an optically distributed broadcast and select switch; wherein   selection by a second node of the set of second nodes of which first node of the set of first nodes to receive a message from is determined by the second node of the set of second nodes.   
     
     
         9 . The method according to  claim 1 , wherein
 the passive optical cross-connect fabric with the set of first nodes and set of second nodes support negative-acknowledgement based layer 4 multicasting.   
     
     
         10 . The method according to  claim 1 , wherein
 each second node comprises a selector which receives as inputs the messages broadcast by the plurality of nodes and selects for its output those messages broadcast by a first node of a plurality of first nodes.   
     
     
         11 . The method according to  claim 1 , wherein
 each second node comprises a selector for dynamically selecting messages from received messages broadcast by the plurality of nodes; and   each first node is connected to the plurality of second nodes via an optical bus and a plurality of taps where each tap of the plurality of taps is associated with a second node of the plurality of second nodes.   
     
     
         12 . A method of multicasting comprising:
 providing a passive optical cross-connect fabric comprising a plurality of first optical cross-connections and a plurality of second optical cross-connections;   providing a set of first nodes each transmitting on a predetermined wavelength of a set of wavelengths;   providing a set of second nodes each transmitting on a predetermined wavelength of a set of wavelengths;   providing a plurality of third nodes each transmitting on a predetermined wavelength of a set of wavelengths; wherein   predetermined subsets of the set of first nodes are connected to predetermined first optical cross-connections of the plurality of first optical cross-connections;   predetermined subsets of the set of second nodes are connected to predetermined second optical cross-connections of the plurality of second optical cross-connections; and   each third node of the plurality of third nodes is connected to another predetermined first optical cross-connection of the plurality of first optical cross-connections and to another predetermined second optical cross-connection of the plurality of second optical cross-connections.   
     
     
         13 . A method of multicasting comprising:
 providing a passive optical cross-connect fabric having a plurality D dimensions, each dimension comprising a plurality of optical cross-connections;   providing a set of first nodes each transmitting on a predetermined wavelength of a set of N wavelengths;   providing a set of second nodes each transmitting on a predetermined wavelength of a set of D wavelengths; wherein   predetermined subsets of the set of first nodes are connected to a first predetermined optical cross-connections of the plurality of optical cross-connections in a predetermined dimension of the plurality D dimensions;   each second node of the plurality of second nodes is connected to D second predetermined optical cross-connections of the plurality of optical cross-connections where each second predetermined optical cross-connection of the D second predetermined optical cross-connections of the plurality of optical cross-connections is within a different dimension of the D dimensions of the passive optical cross-connect fabric such that each second node of the plurality of second nodes is connected to all D dimensions; and   N and D are positive integers.   
     
     
         14 . The method according to  claim 1 , wherein
 the plurality of first nodes comprises M first nodes; and   M=N{circumflex over ( )}D.